1. Field of the Invention
The present invention relates to a motor, a lens barrel, a camera system, and a method for producing the motor.
2. Description of the Related Art
Conventionally, in the case of an oscillatory wave motor which is one type of the motor, an oscillator is subjected to the frictional contact with a relative movement member which serves as a relative movable member. The oscillatory wave, for example, the ultrasonic oscillation or vibration, which is generated on the oscillator, is transmitted to the relative movement member, and the relative movement member is frictionally driven. Therefore, it is necessary that the oscillator efficiently transmits the applied ultrasonic oscillation to the relative movement member. Therefore, a highly elastic material, for example, an iron-based or stainless steel-based metal material is used for the oscillator.
A variety of attempts have been made for the frictional contact surfaces of the oscillator and the relative movement member. U.S. Pat. No. 4,926,085 A1 (corresponding to Japanese Patent No. 2578903) discloses an example in which an alumite layer is provided on one of the frictional contact surfaces, and a nickel layer (Ni layer) is provided on the other of the frictional contact surfaces. The alumite layer herein refers to an oxide coating layer having corrosion resistance formed by performing the anodic oxidation for aluminum.
Any lubricating oil cannot be used for the frictional contact surfaces of the alumite layer and the Ni layer. Therefore, the frictional contact surface principally undergoes the lubrication which is not based on the fluid dynamics, i.e., the so-called boundary lubrication. Therefore, the alumite layer plays a role like the lubricating oil, which greatly affects the transmission efficiency of the ultrasonic oscillation and the function of the oscillatory wave motor.
However, the conventional oscillatory wave motor has involved the following problems. That is, when the frictional contact surface between the oscillator and the movable member is subjected to the frictional driving for a long period of time, the stability of the frictional contact surface cannot be maintained due to the appearance of the abrasion powder generated by any considerable damage of the frictional contact surface resulting from the small difference in hardness between the alumite layer and the Ni layer and/or the deterioration of the alumite layer. Therefore, problems arise such that any abnormal sound or noise is generated and/or the driving efficiency is lowered.
Further, the following problems arise. That is, the frictional contact surface becomes unstable due to the abrasion, and that when the driving operation is performed for a long period of time under the high load, then the number of revolutions is suddenly lowered, it is thus impossible to maintain the stable driving, and the driving performance is deteriorated.
Further, in the case of the conventional oscillatory wave motor using the frictional contact surfaces which are mutually composed of the inorganic materials such as the alumite layer and the Ni layer, for example, a surface treatment is coated on both of the oscillator and the relative movement member. Therefore, problems arise such that the number of working steps is large, and the production cost is expensive. In particular, any masking treatment is required for the elastic member in order to prevent the adhering surface of the electromechanical conversion element from being treated with the surface treatment, because the electromechanical conversion element is to be adhered thereto. Further, problems arise such that large amounts of the time and cost are required for the discarding treatment for discarding the surface treatment liquid.
In addition to the oscillatory wave motor as described above, another oscillatory wave motor is also known, wherein a formed and processed product, which is obtained by forming and processing a resin such as plastic, is used for one of the frictional contact surfaces. However, the forming condition, which is adopted to form the resin, greatly affects the physical property of the formed and processed product. Therefore, the following problem arises. That is, it is difficult to select the optimum forming condition under which the formed and processed product of the resin is provided with the optimum physical property to be used for the frictional contact surface.
In order to use the formed and processed product for the frictional contact surface, it is necessary that the cutting machining is coated on improve the dimensional accuracy. Usually, for example, a conductive carbon filler is added as a frictional coefficient-increasing agent to the formed and processed product of the resin. However, any considerable damage is caused on the blade of the cutting tool due to the conductive carbon filler or the like. Therefore, it has been impossible to increase the cutting velocity. Further, it is also necessary that the cut and processed product is joined to the elastic member, for example, with an adhesive. In consideration of such circumstances, the following problem arises. That is, when the formed and processed product of the resin, which is added with, for example, the conductive carbon filler as the frictional coefficient-increasing agent, is used for the elastic member, then a long period of time is required for the processing, the production cost becomes expensive, and it is difficult to obtain any desired dimensional accuracy.